The invention relates to the general field of cooling of psychrometric mixtures.
It is understood that a psychrometric mixture contains two types of gas, specifically:                a first type of gas which, under temperature and pressure conditions cannot go to the liquid state; and        a second type of gas under conditions where it can either condense or evaporate.        
By way of example, humid air is an example of a psychrometric mixture, comprising:
dry air not condensing under normal temperature and pressure conditions; and
water vapour capable of either condensing or evaporating as a function of temperature and pressure conditions.
Fumes from combustion units, (or more generally any gaseous effluent comprising gases of air in variable concentrations and compounds such as CO2 and H2O) are other examples of psychrometric mixtures. In general, combustion fumes are psychrometric mixtures having a substantial concentration in water vapour.
Other less common psychrometric mixtures are known, especially mixtures of helium and ammonia and mixtures of hydrogen and ammonia.
The document FR 2 820 052 describes an extraction process of carbon dioxide contained in fumes, in which the fumes are cooled at a pressure substantially equal to atmospheric pressure and at such a temperature that carbon dioxide moves directly from the vaporous state to the solid state by a process of anti-sublimation, water also being extracted in liquid form by an air exchanger, for example.
This type of system, though particularly advantageous, does not unfortunately recover the coolness of the cooled gases over a wide temperature range. Nor does it carry out boosted dehumidification of dry fumes, at low cost.